Polynaphthalene was studied since the 1960s because of its excellent heat resistance and optical performance. So far, as organic electroluminescent materials and lithium ion secondary battery materials, they have been widely used in the field of functional organic photoelectric materials. Meanwhile, polyethylene naphthalate which is produced from precursor of naphthalene dicarboxylic acid has been used as a unique polymer material alternative to glass in carbonated drinks and beer packaging industry due to its excellent gas barrier properties.
From 1990s, with the development of microelectronics industry, 90-nanometer chip manufacturing industry based on copper interconnection technology has made many demands for the material industry, among which the most urgent one is a material having both low dielectric constant and high heat resistance quality. Dow Company had developed several low dielectric materials. In addition to the famous SILK, a silicon-containing benzocyclobutene was developed. The oligomers which are obtained after prepolymerization treatment of these materials have good film-forming properties. After further curing with heating, solid films with dielectric constant up to 2.5 can be obtained. However, these materials are expensive, so it is necessary to develop inexpensive materials. Since the outstanding characteristics of polynaphthalate, Ueda et al. in Japan developed binaphthyl ether polymers (see Macromolecules 2004, 37, 4794 and Macromolecules 2006, 39, 3964). These materials have outstanding heat resistance qualities and are inexpensive. However, the dielectric constants of these materials are greater than 2.5, so the electrical properties are inferior to those of Dow's products.
It is known that the fluorine-containing polyaryl ethers have low dielectric constant and high heat resistance. However, the synthesis of fluorine-containing polyaryl ether involves using expensive perfluoro-benzene, thus greatly increasing cost of materials. In recent years, polyperfluorocyclobutane (PFCB) polymers from tetrafluoroethylene attract high attention from people, because these polymers have not only relatively low cost, but also high temperature resistance quality, chemical stability, excellent electrical properties, low moisture absorption and good mechanical properties (see WO9015043). However, since the [2+2] cycloaddition reactions occur at high temperatures of trifluoromethyl vinyl ether, which is a precursor of perfluorocyclobutane, usually tend to be incomplete, the heat resistance and dielectric properties of film are unstable. It should be particularly noted that such polymers often contain unreacted trifluoromethyl vinyl ether end groups, which are susceptible to attack from nucleophilic reagents, so that they are defluorinated, thereby lowering performance of materials (see Chem. Commun., 2006, 4844-4846).
Summing up, there is an urgent need in the art to develop a polymer material of low-cost, good electrical properties, and stability to heating.